Posted by
K9MA on
Nov 28, 2018; 4:33am
URL: http://elecraft.85.s1.nabble.com/KPA-1500-issues-tp7646571p7646600.html
I think the point Mike is trying to make is that many SWR meters don't
actually measure SWR all that accurately as impedance changes. While the
length of transmission line doesn't affect SWR (other than the effect of
loss), the impedance at a given SWR does change with line length, and
that may cause the indicated SWR to change with some instruments. I
wonder if an antenna analyzer, which actually measures impedance, and
calculates SWR from that, would do any better. If it measures impedance
accurately, it should.
73,
Scott K9MA
On 11/27/2018 21:34, Wes Stewart wrote:
> I fail to see what that will prove. The only length that will do
> anything exciting is the 1/4 wavelength line and even that doesn't
> affect the SWR. The other two will just repeat (less loss) on the
> input side, what terminates the load side.
>
> Wes N7WS
>
> On 11/27/2018 3:51 PM, Michael Walker wrote:
>> If you truly want to understand SWR, I recommend you pick a frequency
>> and
>> make up a 1/4, 1/2 and 1 wavelength sections of 50ohm coax.
>>
>> Then measure the SWR at those points into various different resistive
>> loads, like 10, 25, 50, 75, 100, 150 and 200 ohms.
>>
>> I think you will find the results very interesting.
>>
>> Mike va3mw
>>
>
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